Photographic enlarger



Nov. 1, 1938. A. GRANT 2,135,074

PHOTOGRAPHIC ENLARGER Filed June 21, 1957 2 Sheets-Shet 1 i .w' o .53

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i W 0kg J7== W BY g M ATTORNEY.

Nov. 1, 1938 A. GRANT PHOTOGRAPHIC ENLARGER Filed June 21, 1957 2Sheets-Sheet 2 iiiiil I N VE NTOR.

Patented Nov. 1, 1938 UNITED STATES PATENT OFFICIE 4 Claims.

This invention relates to a photographic enlarging machine and has forits principal object the provision of a highly eiiloient device for useon the modern miniature camera films for rapidly producing enlargedprints of said films.

Other objects of the invention are: to provide an enlarging machine inwhich an automobile globe may be efficiently employed for the lightsource; to provide efficient means for cooling the condensing lenses andthe lamp housing to prevent undue heating thereof; to provide anenlarger which can be rotated in a horizontal plane about its supportingstandard so that the image may be projected downward upon a base boardor beyond the edges of said board upon the floor to produce enlargementsof any desired size; to provide a machine of this character in which thelamp housing and projector may be rotated in a vertical plane about itssupporting standard so that the image may be projected upwardly,downwardly, or horizontally so that it may be used to project slidesupon the wall or ceiling of a room; to provide a film support in anenlarging machine which may be rotated so that the position of the imagecan be turned or inverted without removing the film; to provide acombined supporting standard and transformer housing which willeliminate the number of parts necessary and produce an ornamentalappearance; to provide a demountable standard by means of which theentire upper structure can be quickly and easily demounted for packingand transporting; and to provide a highly efiicient, rotatable papermask frame for holding the printing paper which will allow the latter tobe rapidly and quickly changed to produce enlargements in commercialquantities.

The invention is more particularly designed as an improvement over themachine illustrated and described in applicants Patent No. 2,001,026.

Other objects and advantages reside in the detail construction of theinvention, which is designed for simplicity, economy, and efliciency.These will become more apparent from the following description.

In the following detailed description of the invention reference is hadto the accompanying drawings which form a part hereof. Like numeralsrefer to like parts in all views of the 50 drawings and throughout thedescription.

In the drawings:-

Fig. 1 is a perspective View of the enlarging machine.

Fig. 2 is a detail vertical section through the base of the supportingstandard.

Fig. 3 is a detail section through the printing paper frame.

Fig. 4 is a vertical enlarged section through the projecting mechanism.

Fig 5 is a slide elevation of the projecting 5 mechanism with the filmplate in the open position.

Fig. 6 is the detail section through the bracket pivot.

Fig. '7 is a detail view of a film masking plate 10 as employed in theenlarger.

The enlarger employs a base board ID, at one extremity of which atransformer housing II is secured to enclose a suitable transformer I2.

A suitable toggle switch 33 may be used to control the supply of currentto the transformer I2. This current may also be controlled by means of apress button 34 on the base board I!) when the device is being used forrapid printing.

On top of the transformer housing is a socket I3, provided with alocking screw I4, for receiving and locking in place a tubular standardI5. A bracket I6 projects from the standard E5. The bracket is providedwith a split sleeve I1 which is clamped about the standard I5 by meansof a clamp screw I8.

The projector portion of the device consists of a cylindrical lenshousing I9 provided with a stud 20 which fits into the extremity of thebracket IS. The stud 20 is rotatable within the bracket and is held at90 positions of rotation by means of a locking ball 2| which enters 90spaced receiving sockets 22 in the stud. The ball is constantly pressedagainst the stud by means of a compression spring 23, the pressure inwhich is regulated by means of a set screw 24. This construction allowsthe lens housing I9 to be rotated and gives a click to indicate to theoperator when the housing is accurately in any of the desired horizontalor vertical positions.

A lamp housing 25 fits telescopically over the lens housing I9 and islocked thereon by means of .a suitable bayonet joint 26. The lamphousing is provided with a sleeve 21 for slidably receiving a lampreceptacle 28 of the automobile type. The socket may be locked at anydesired degree of extension by means of a set screw 29. A singleconductor cord 30 leads from the receptacle 28 downwardly through thestandard IE to a connector 3I therewithin. The connector 3| isdetachably connected to the feed wires from the transformer 2I. The cordis insulated from the standard at its upper extremity by means of aninsulating cap bushing 23.

This construction allows the standard I5 to ing an internal partitionplate 56.

be lifted from its socket and the cord disconnected at the connector 3!so that the entire device may be laid flat upon the base board Ill.

The lamp housing 25 is provided with an internal, heat insulating shelland with ventilation openings 36 in its top. A baffle plate 31 and abaffle ring 38 prevent the light shining through the openings 36. Thelens housing 19 is provided with an internal lens sleeve 39 of heatinsulating material in which are three condensing lenses, designatedupper, intermediate and a lower condensing lens 40, 4| and 42,respectively.

The lower condensing lens 42 is supported on a lens plate 43, referablyof Bakelite or similar material. The lens board 43 is rotatably attachedto the housing [9 by means of a pair of arcuate attachment plates 44which overlap a flanged lower extremity on the housing [9 and allow theplate 43 to be freely rotated thereon. The intermediate lens 4! issupported above the lens 42 by means of a coil spring 45, and the upperlens is supported upon a supporting ring 46 upon the intermediate lens4|.

The entire assembly is constantly pressed against a perforated annularflange 41 in the upper face of the housing l9. The lower portion of thehousing i9 is perforated as shown at 48. This allows a free flow of airthrough the perforations 38 upwardly about the lens sleeve 39, throughthe perforated flange 41, through the lamp housing, and through thedischarge openings 36, thus keeping the entire structure air cooled atall times.

A hinged film plate 49 having the same contour as the lens plate 43 ishinged to the latter upon a suitable hinge 50. The other extremity ofthe plate 49 contains a spring clip 5| which snaps over the plate 43 tohold the two plates in parallel relation. A film supporting member 52extends across the lower board terminating at its extremities in filmpockets 53 for holding the rolls of film.

A flanged projection tube 54 is secured to and extends downwardly fromthe lower plate 49. The tube 54 slidably contains a lens tube 55 hav- Asuitable projection lens assembly 51 is threaded into the plate 56 andis protected by the lower extremity of the tube 55. The tube may beadjusted to the desired focusing position and locked in place by meansof a knurled clamp screw 58 which passes through a diagonal slot 59 inthe tube 54.

A film channel 60 extends across the lower plate 49. Two spring arms 6|extend across the film channel therein to hold the film. The center ofthe plate 49 is cut away to the diameter of the tube 54. This opening issurrounded by a countersunk depression into which removable film masks62 are inserted. A typical film mask is illustrated in Fig. 7. Thesemasks are notched, as shown at 63, and the counterbore for receivingthem is formed with a projection 64 fitting the notch so that the masksare always positioned in the proper position. Each mask is formed with afilm channel 65 extending thereacross and each is provided with a maskopening 66 to accommodate the particular size of film for which thatparticular mask is intended.

The bottom of the film channel 65 in the mask aligns with the bottom ofthe film groove 60 in the plate 49 so that the film travels straightthrough the machine. At the point where the film crosses the lightopening, a circular glass plate 67 is positioned. The plate 51 fits intocounter-sunk arcuate side depressions in the plate 49 so that its upperface is flush with the upper face of the plate. The glass plate ishinged by means of a piece of adhesive tape 68. Adhesive tape has beenfound to be the best substance for this purpose, as it attaches readilyto the glass and Bakelite surfaces, and yet can be easily detached,should it be desired to remove the glass for cleanmg.

A printing board 69 for supporting the paper upon which the enlargementis to be made is mounted over the base board It]. The printing board ispivoted upon a pivot bolt '10 extending through a base member H which inturn is attached to the board I0 by means of suitable attachment screws12. A compression spring 13 acts against the head of the bolt 20 toconstantly hold the printing board 69 downwardly against the basemember. The base member is grooved at 90 positions, such as shown at 14,and a click ball 15 is forced downwardly from the bottom of the printingboard by means of a spring 16 so that, as the frame is rotated, it willclick into the notches 14 to definitely stop the frame at 90 positions.The upper face of the board is open on one side, and is surrounded by araised edge on the other three sides. A rectangular mask frame 11 ishinged at 18 to the back of the board, and falls by gravity into theopen face thereof to hold the paper sheet in place and provide a whiteborder therearound.

The usual miniature picture is so small that it is not desirable. Usersof miniature cameras therefor prefer to have these pictures enlarged. Atpresent this enlarging is rather a tedious and an expensive proceeding.With this machine, however, enlargements can be made with rapidity equalto the making of the usual contact prints.

Let us assume that it is desired to produce enlargements to 3 x 4inches. A 3 x 4 printing board is placed upon the plate H. The film rollis inserted through the machine below the glass plate 69 and a perfectfocus is obtained by means of the adjustment of the lens sleeve 55.However, if this type of work is regularly being done, the adjustmentwill already be set. The operator now slides his paper into the frame69, drops. the mask 11 thereon, presses the button 34 the required timeinterval, releases the button, lifts the mask. and removes the paper. Hethen slides the film t0 the next picture and repeats the operation until the entire length of film or the desired portions thereof areprinted. Should he come upon a picture taken vertically, he can eitherturn the film plate of the projector 90 or turn the printing board 90 toproperly position the picture on the paper.

For larger enlargement work, the base plate H can be removed, and thepaper placed directly upon the base board 10. For still larger work, thepaper may be placed upon the wall of the room or the floor thereof,since the machine is adaptable to projection to any point.

To more evenly distribute the light, it has been found advisable tofrost the upper surface of the intermediate lens 4|. To provide a safelight which may be used for safely adjusting the paper under theilluminated image, a curved slot 19 is formed in the upper plate 43 forthe insertion of a flexible strip of red Celluloid or similar material80. When the strip 80 is slid into the slot 19, it will slide completelyover the light opening in the lens housing so as to cause a red light tobe projected. Additional light either white or red can be provided foruse on the work table by allowing the lower board 49 to hang in the openposition of Fig. 5.

While a specific form of the improvement has been described andillustrated herein, it is desired to be understood that the same may bevaried, within the scope of the appended claims, without departing fromthe spirit of the invention.

Having thus described the invention, what is claimed and desired securedby Letters Patent 1. In an enlarging machine, a condensing lens housing;a film supporting plate rotatably mounted below said housing so that itmay be rotated about the axis thereof; a lens tube extending from saidfilm plate and rotatable therewith; and a projection lens assemblymounted in said lens tube; there being a slot through said lens plate;and a flexible, red, transparent strip inserted through said slot tocolor the light passing through said plate.

2. In a photographic enlarger of the type hav ing a vertical cylindricallamp housing containing a light source, means for rotatably mounting afilm supporting means and projection lenses thereon, comprising: a lensboard; a second board hinged to said lens board so that it may be swungdownwardly to allow a film to be inserted between said two boards: alens tube secured to and projecting from said second board; projectionlenses in said lens tube; and means for rotatably mounting both boardson the extremity of the lamp housing so that they may be freely rotatedabout the axis of said lamp housing.

3. In a photographic enlarger of the type having a vertical cylindricallamp housing containing a light source, means for rotatably mounting afilm supporting means and projection lenses thereon, comprising: a lensboard; a second board hinged to said lens board so that it may be swungdownwardly to allow a film to be inserted between said two boards; alens tube secured to and projecting from said second board; projectionlenses in said lens tube; a flange formed about one extremity of saidlamp housing; and means for movably supporting said lens board on saidflange so that it may rotate about the axis of said lamp housing.

4. In a photographic enlarger of the type having a cylindrical lamphousing containing a light source, means for rotatably mounting a filmsupporting means and projection lenses thereon, comprising: a lensboard; a second board hinged to said lens board so that it may be swungdownwardly to allow a film to be inserted between said two boards; alens tube secured to and projecting from said second board; projectionlenses in said lens tube; a flange formed about one extremity of saidlamp housing; means for movably supporting said lens board on saidflange so that it may rotate about the axis of said lamp housing; and agroove formed in the upper face of said lens board extending beneathsaid flange to allow an insert to be pushed beneath the flange and oversaid lens board.

ALVIN GRANT.

